Process of extracting turpentine and rosin from resinous wood



\ Patented Aug. 19, 1924.

' United States,

UNITED STATES 1,505,438 PATENT OFFICE.

CLARENCE SHERWOOD AND RAYMOND K. CO'LE, OF BRUNSWICK, GEORGIA, AS-

SIGN OBS TO HERCULES POWDER COMPANY, OF WILMINGTON, DELAWARE, A GOR- PORATION OF DELAWARE.

PROCESSOF EXTRACTING- TURPENTINE AND ROSIN FROM RESINOUS WOOD.

No Drawing.

To all whom it may concern:

Be it known that we, CLARENCE M. SHER- woon and RAYMOND K. COLE, citizens of the residing at Brunswick, county of Glynn, and State of Georgia, have invented a new and useful Improvement in Processes of Extracting Turpentine and Rosin from Resinous Wood, of which the following is a full, clear, and exact description.

It is known in the art to extract turpen tine and rosin from coniferous woods. Various processes have been employed, and while some have been successfuhthe quality of the rosin obtained has been distinctly inferior to gum rosin, wholly or largely because of the presence inthe final product of color bodies, that could not be eliminated.

A typical known process comprises the extraction of the wood with a volatile hydrocarbon solvent to obtain both rosin and turpentine. The extract is then distilled to remove, first, the solvent and then the that may not have been removed by extractionwith steam, are driven ofl in an evaporator, leaving behind the rosin. This steam solvent process is described more in detailin the Walker Patent No. 922,369, dated May 18, 1909. In the commercial practice of the process, the quality ofthe pine oil and turpentine is very high, and the prices obtained for such products are comparable with prices of similar products produced from the living tree, or, as commercially known, gum products. The rosin produced, however, while of commercial value, and adapted for different uses, as, for example,

. the sizing of dark-colored paper, cannot be used for many purposes, such as sizing white or light-colored paper and the manufacture 1921. Serial No. 470,684.

of soap. It is, in fact, of such an inferior quality as to command a considerably lower price than gum rosin, which fact, together with the limited market for which this product is suitable, makes the practice of this industry ordinarily unprofitable, even though the liquid products are of a high grade.

The object of our invention is to so modify and improve the last mentioned process that the rosin recovered will be of superior quality, comparable with that of gum rosin and adapted for all the uses to which a high grade gum rosin is applicable, including soap making, sizing of white paper, manufacture of high grade varnishes, etc.

In the practice of our process, we obtain such a rosin which is of such high quality as to command prices comparable with those procurable for the natural gum roducts, which fact, together with the unlimited field of application, puts the industry on a commercially sound basis.

While our improved process contains steps which are additional to those heretofore used, thereby somewhat adding to the cost, we have succeeded in dispensing with other steps heretofore considered necessary, so that the much higher value of the rosin yield is not obtained at a necessarily increased cost.

We shall now describe the entire process,

but shall avoid any detailed description ofthe turpentine recovery steps of the process, it being understood that this is substantially the same asv that known in the art. For a more complete description, reference may be made to the Walker Patent No. 922,369 above mentioned.

The wood, which is preferably in the shape of sawdust or fine chips, is extracted with steam under ten to twenty pounds absolute pressure. The steam and turpentine vapors carried ofl thereby are led to a condenser, after which the condensed water and turpentine are separated by gravity.

The distilled wood, thus freed from turpentine, and containing the residual rosin, is then extracted with a volatile solvent capable of dissolving rosin. Preferably this solvent is gasoline. Any other volatile hydrocarbon may be used. In fact, any low boiling, chemically neutral solvent is capable of use. The solution that is drained ofi consists of the solvent, rosin, a little turpentine, a little coloring bodies.

So far as is above described, the process is well known. It is also well known that in the solvent extraction step of the process, a large percentage of the rosinusually about forty per cent-is left in the wood. Therefore it is customary to repeat the solvent extraction process a number of times pine oil and objectionable until nearly all the rosin has been extracted.

It has been assumed,-in prior processes, that the original portion of solvent. was ineffective to dissolve all the rosin and that the treatment with other portions of solventwas required to effect a solution, and hence a removal, of the remaining rosin. Careful experiment and prolonged study, however, have convinced us that practically all the rosin is dissolved in the first solvent treatment, and that what remains in the wood is a solution containing practically the same proportionsof solvent and rosin as is contained in the solution .that is originally drained off. t

We have succeeded in recovering practically all the rosin without the use of any additional portions of solvent. Instead of adding more solvent, we add water at about boiling temperature, or we add water under pressure (super-heated water). The water displaces the rosin solution, which by gravity rises to the surface and is decanted ofi.

Not only does the use of water as a displacing medium eliminate the handling of large quantities of solvent, but it also renders recovery of such solvent very much more complete,thereby reducing the cost of our process to very considerable degree. Further, the use of this displacement process entirely eliminates the cost of power necessary for handling large amounts of solvent and the cost of steam which has heretofore been necessary to volatize the solvent remaining in the wood for the purpose of re-' covering same. i

It should be noted that in the application of this water displacement process, the same water can be used repeatedly, and by prop erly insulating receivers and pipe lines, in practice very little heat is lost through radiation.

The next step in the process is the treat- .ment of the rosin solution, part of which has been drained oil and the remainder recovered by displacement with superheated or boiling water, as described. As hereinbefore stated, the rosin solution-contains objectionable coloring matters, which are not driven oil by distillation of the solvent. Nor

can the rosin, after separating from the solvent, be purified by liquefaction and filtration, or by any other known treatment. We have discovered, after long experimentation and careful research, that the objectionable properties of the rosin are due to 5 precipitated from colloidal solution by interaction with another colloid of opposite sign. This principle has been made use of in the application' of our process for removing objectionable coloring matters from rosin. f

Our investigations having shown that the solution .of gasoline-rosin-coloring bodies is i in a colloidal condition in which the rosin and coloring bodies exert a certain positive or negative electrical charge, our problem has been to find some other colloid of opposite sign to that possessed by the coloring matters and which should brmg about precipitation.

We have found that bone black or other decolorizing carbons possess the property of precipitating certain color bodies which have had a deleterious effect on the manufacture of paper size, but the use of decolor-- izing carbon has resulted in a rosin the'color of which is not improved and is, under someconditions, darker than that of the original rosin before treatment. This henomenon ma be explained, perhaps, by t e fact that col oidal carbon apparently possesses the same sign as the color bodies existing in solution with the rosin in petroleum.

We have discovered however, that if we use as a filtering medium a. colloidal substance of opposite sign to the coloring matters contained therein, such a filtering medium will precipitate the color bodies that exist incolloidal' condition in the rosin-petroleum solution, and which is due to the fact above outlined. That is, colloids possessing opposite electrical charges precipitate one another. A limited class of such filtration media have been found to possess the desired characteristics.

Fullers earth has been found to be the I most satisfactory. Other similar bodies,

among which may be included diatomaceous earths, while less desirable, may, under certain conditions, be used. Colloidal sulphur is another substance that is practically efiicacious, although not perhaps commercially practicable.

Preferably the solution is pumped through a body of fullers earth, but any other known procedure may be utilized. The gasoline and any turpentine and pine oils which may not have been removed in the turpentine distillation step are recovered in evaporators, the rosin remaining behind as a residue, being free of coloring bodies, and of a very high grade that may be marketed competitively with gum rosin.

While the filtration step of my process is applicable to rosin produced from resinous or light woods, it is also adapted to the de colorization of rosin produced by tapping the living tree.

The filtering medium, as a result of this step of the process, has been contaminated not only with the coloring bodies of the rosin, but also with some rosin and solvent. It may be purified for re-use in several ways, of which two may be described. (1) Add water, preferably boiling water or superheated water in volume in excess of the filtering medium. The water displaces a large part of the contaminating matter rosin, gasoline and coloring bodies, which float on the water and may be decanted off. After, draining off the water, steam is forced through the filtering medium.

(2) Calcine, by placing the filtering medium in an indirectly heated retort or kiln and preserving the volatile products by distillation and condensation.

If the filtering medium has been used until its decolorizing powers have become exhausted, it may be rendered fit for use by treating with heated benzol, toluol or other aromatic hydrocarbons, or in fact, with any solvent which possesses the property of dissolving the color bodies which have been removed by the filtering medium. By passing dry steam through the filtering medium after this solvent treatment, the last traces of solvent adhering to the filtering medium may be recovered.

While this process for purifying the contaminated filtering medium is more expeditiously accomplished by the use of a heated solvent, we do not limit ourselves to any particular degree of temperature, as some solvents, for instance alcohol, act al most as well-in the cold as in the hot.

Having now fully described our invention,

what we clai'm'and desire to protect by Letters Patent is: v

1. The process of recovering, from resinous wood, turpentine and rosin, which comprises distilling off turpentine from the wood at a temperature insuflicient to injure the rosin, and then removing the rosin by with hot water the rosin solution still remaining in the Wood, substantially separating the rosin solution from the water, and substantially separating the rosin from the solvent: and, in order to minimize the loss of heat, rosin and solvent, utilizin the separated solvent for extracting anot er batch of Wood, thereby saving any rosin that has not been removed from the solvent, and utilizing the separated water for displacing the rosin remalning in the second batch of wood, thereby conserving the latent heat of the water and saving any solvent and rosin that have not been removed therefrom.

3. The process of recovering rosin from resinous wood which comprises extracting the Wood with a solvent, draining ofi' the solution of solvent and rosin, dlsplacing with hot water the rosin solution still remaining in the wood, substantially separating the rosin solution from the Water, treating the two rosin solutions with a filtration medium to remove color bodies, and substantially separating the rosin from the solvent: utilizing the se arated solvent for extracting a second bate of wood, thereby saving the rosin that has not been separated from the solvent; utilizing the separated water for displacin the rosin remaining in the second batch o wood, thereby conserving the latent heat of the water and saving any solvent and rosin that have not been removed therefrom; treating the filtration medium to extract at least some of the solvent and color bodies; and using the treated filtration medium for treating other batches of rosin solvent to remove color bodies.

In-testimony of which invention, we have hereunto set our hands, at Brunswick, on this 14th day of May, 1921.

CLARENCE M. SHERWOOD. RAYMOND K. COLE. 

